Some
70% of women with early-stage breast cancer and an intermediate risk of cancer
recurrence can safely skip chemotherapy after their tumours have been removed,
U.S. researchers said on Sunday.
“This
is a major finding,” said Dr. Larry Norton, a breast cancer expert at Memorial
Sloan Kettering Cancer Center in New York, who helped organise the
government-funded study more than a decade ago.
“It
means that maybe 100,000 women in the U.S. alone do not require chemotherapy,”
Mr. Norton said.
The
research, presented at the American Society of Clinical Oncology (ASCO) meeting
in Chicago, studied how to treat women with early-stage breast cancer that
responds to hormone therapy.
Women
were deemed to have a medium level risk of the cancer coming back based on a 21-gene
panel known as Oncotype DX from Genomic Health. The test predicts the
likelihood of cancer recurrence within 10 years. Those who score low on the
test — from zero to 10 —are already told to skip chemotherapy after their
tumours are removed and they receive hormone therapy. Those who score high — 26
to 100 — receive both hormone therapy and chemotherapy.
The
study, dubbed TAILORx, was also published in the New England Journal of
Medicine. It involved more than 10,000 women with breast cancer that had not
spread to nearby lymph nodes and whose tumours respond to hormone therapy and
test negative for the HER2 gene. Of those, 6,711 scored in the intermediate
range of 11-25, and were randomly assigned hormone therapy alone or hormone
therapy plus chemotherapy.
The
study found that all women over 50 with this type of breast cancer could skip
chemotherapy, a group that represented 85% of the study’s population. In
addition, women 50 and younger who scored between zero and 15 could be spared
chemotherapy and its toxic side effects.
Some
benefits
However,
chemotherapy did offer some benefit to women aged 50 and younger who had a
cancer recurrence score of 16-25, researchers found. Dr. Steven Shak, chief
scientific officer at Genomic Health, said about four in 10 women in the U.S.
with early stage breast cancers are not tested for recurrence risk. He expects
the study’s results will change that practice.
“This
is going to provide the highest level of evidence now for our test being
indispensable in clinical practice,” Dr. Shak said.
The
company currently provides tests to more than 900,000 patients in more than 90
countries, Dr. Shak said. In the United States, the test costs $4,000 and is
covered by Medicare and all major private insurers.
